Currently, brake system master cylinders are equipped with a brake fluid reservoir installed on one or both of the master cylinder's supply fittings, depending on whether the master cylinder is simple or tandem. The brake fluid in the brake fluid reservoir or discharged during the braking and ESP system operation phase passes freely from the reservoir into the chamber or chambers of the master cylinder.
If the reservoir is unmounted for maintenance, it must be emptied to prevent brake fluid from spilling.
In the event of an accident, if the reservoir is torn from the master cylinder, the brake fluid, which is combustible, may reach the very hot surfaces of the engine and cause a fire.